1. Field of the Invention
The present invention relates to a thermostat capable of resetting a switching contact of the thermostat to initial state by force by remote control operation, and a heating apparatus using this thermostat.
2. Description of the Related Art
A thermostat is an electric part for on/off control of a switching contact by sensing the ambient temperature, and changes of ambient temperature are sensed by a heat sensing element (a bimetal disk). The heating sensing element is displaced in its curvature state when its temperature exceeds a first set temperature, and later returns to the initial curvature state when the temperature of the heat sensing element drops below a second set temperature, and the on/off state of the switch contact is shifted by making use of this property.
The thermostats are classified into the automatic reset type thermostat which is automatically reset to the initial state in the usual operating state of the apparatus in which the thermostat is incorporated (that is, in normal state), and the manual reset type thermostat which is not reset to the initial state in normal state unless manipulated by man.
In the automatic reset type thermostat, when the temperature of the heat sensing element exceeds the first set temperature, the switching contact is changed, for example, from ON state to OFF sate, and then when becoming lower than the second set temperature (automatic reset temperature), the thermostat automatically returns to the initial ON state, and typically it is used for the purpose of maintaining the apparatus comprising the thermostat within a specified temperature range.
In the manual reset type thermostat, on the other hand, once the switching contact is changed, for example, from ON state to OFF state when the temperature of the heat sensing element exceeds the first set temperature, in the usual operating state of the apparatus, it is held in the OFF state unless manipulated by man. Keeping the switching contact in OFF state is useful for preventing recurrence of abnormal state, and it is achieved, for example, by setting the automatic reset temperature of the bimetal disk below the ordinary temperature (for example, -30.degree. C.).
FIG. 18 shows a manual reset type thermostat having the automatic reset temperature of bimetal disk set below ordinary temperature. In this manual reset type thermostat 70, once a bimetal disk 71 is displaced physically, it is not reset automatically to the initial state in normal state. If necessary, hence, a guide pin 73 is pushed up by a reset button 72 to return the bimetal disk 71 to the initial state (the shown state).
However, the manual reset type thermostat as shown in FIG. 18 is very inconvenient because the mounting position is limited.
For example, suppose to incorporate the manual reset type thermostat 70 in a cooking utensil 74 as shown in FIG. 19. The cooking utensil 74 comprises a heater 75, a cooking unit 76 heated by the heater 75, and a case 77 housing the heater 75 and cooking unit 76, but in this cooking utensil, since the place A suited for the user to manipulate the reset button 72 and the place suited for the bimetal disk 71 for sensing the heat are not matched, the thermostat 70 is installed in an intermediate position, which makes it very inconvenient to use.
Incidentally, it may be considered to manipulate the reset button 72 from a remote plate by making use of leverage or the like, but the entire mechanism is complicated, and it is difficult to assemble the apparatus, which is not regarded as a reasonable means of solving the problem.
The invention is devised to solve the problem and it is a primary object thereof to present a thermostat for remote control operation capable of installing the heat sensing element in an appropriate position, and manipulating to reset at an arbitrary position.